The invention relates to apparatus for the separation of the reusable part from the unusable part of granular form filter material from filter equipment, particularly the reusable part from the unusable part of granular form activated charcoal.
An area of use of filter equipment based on activated charcoal granules is, for example, in printing in which it works with solvent-containing dyes. The printed article is led through a drying apparatus after the printing process, where the solvent evaporates under supply of warmer air. The air laden with solvent is passed into the filter equipment in order to filter out the solvent from the air. After a certain working time, the filter material, i.e. the activated charcoal, becomes saturated and the solvent must be driven off from the filter material by steam or the like. The solvent material driven off can then, if desired, be recovered by a subsequent distillation process. Through the constant change between filtering out of the solvent from the air and driving the solvent out from the filter material by steam, in the run of time increasingly more grains of the activated charcoal granules decay whereby the filter process is considerably diminished and, moreover, the pressure of the steam must be raised in order to drive off the solvent from the granules. From time to time the granules must be therefore taken out of the filter equipment and separated into reusable and unusable parts. For this one has since long ago sucked the granules out of the filter housing by means of a suction device and accumulated then on the ground. The accumulated granules were then thrown by means of a hand shovel against an inclined flat sieve, in order to sieve out the smaller particles from the granulate material. Through the fact alone that the activated charcoal granules withdrawn from the filter equipment were first of all thrown onto the floor and were then hurled against a sieve by means of a shovel, a large amount of broken grains arose, whereby the proportion of non-reusable granules considerably increased. Moreover the work connected with the sieving is extraordinarily time consuming and accompanied by a considerable discharge of dust into the environment. Additional difficulties arise in that the filter equipment as a rule is arranged not in readily accessible places.
A separating or sieving apparatus is also known in which granular form filter material is transferred by hand or through a supply device onto a reciprocating riddle for separation into the reusable and unusable parts. Because of the high relative movement between riddle and granulate form filter material, this is subject to high abrasion similar to working with an inclined flat sieve.
The underlying object of the invention is to provide an apparatus of the kind set out in the introduction with which the granular form filter material, particularly activated charcoal granules can be withdrawn from the filter equipment and effectively separated into unusable and reusable parts in a more gentle and environmentally acceptable manner and also with less expenditure of work. The apparatus should further have a simple and robust construction and meet the requirement of ensuring rapid deployment in inaccessible places.
The apparatus according to the invention for separation of the reusable part from the unusable part of granular form filter material from filter equipment is characterised by a base frame, a sieve drum for sieving of granular form filter material rotatably mounted on the base frame, means for driving the sieve drum and means for pneumatic withdrawal of granular form filter material from the filter equipment and for feeding the material to the sieve drum.
The apparatus for pneumatic withdrawal of granular form filter material from the filter equipment and for the feeding of the material to the sieve drum can, according to a further aspect of the invention, include a suction container arranged on the base frame with an inlet opening for reception of granular form filter material from the filter equipment and an outlet opening in working connection with the sieve drum, means for closing and opening the outlet opening, and means for producing a reduced pressure in the suction container and creating a suction force on the inlet opening during the time in which the outlet opening is closed. The pressure reduction pump as well as a flap for closing the outlet opening of the suction container can be periodically operated by means known per se so that the flap is closed during the time in which the pressure reduction pump is in use and the flap is open during the time in which the pressure reduction pump is out of use.
Through alteration of the suction force of the pressure reduction pump and/or the time during which the suction force acts on to the inlet opening of the suction container or the outlet opening of the suction container is closed, the amount of charge of granular form filter material withdrawn from the filter equipment and fed to the sieve drum can be adjusted.
In order to be able to alter or adjust the throughput speed through the sieve drum of the filter material, the longitudinal inclination of the sieve drum and/or the rotational speed can be altered. For this purpose a sub-frame can be pivotally mounted on the base frame, in which sub-frame the sieve drum is journalled rotatably, and the sieve drum can be driven by, preferably, a variable speed motor driven by air pressure.
By adjustment of the longitudinal inclination and/or the rotational speed and/or the amount of granular form filter material charged to the sieve drum per unit time, optimal sieving conditions for gentle and effective treatment of material can be obtained.
A preferred alternative embodiment of an apparatus built according to the invention is characterised by a base frame, a sieve drum rotatably mounted on the base frame, the longitudinal inclination of the drum relative to the base frame being adjustable; means for driving the sieve drum with variable rotational speed, conduit means, which is in working connection with the sieve drum at one end and, at the other end, is connected to suction/pressure supply means for pneumatic withdrawal of granular form filter material from the filter equipment and production of a flow of pressure medium through the conduit means, in order to move the withdrawn granular form filter material under pressure through the conduit means to the sieve drum, means arranged on the base frame between the conduit means and the sieve drum for creation of an increased flow cross section for the granular filter material, in order to move this with reduced speed to the sieve drum, and means for adjustment of the amount of filter material withdrawn and fed to the sieve drum per unit time.
This embodiment of the invention makes possible,whilst maintaining gentle handling of the granular form filter material or active charcoal, a continuous withdrawal of material from the filter equipment and continuous processing of it in the sieve drum. Because of the supply of filter material from the filter equipment to the sieve drum by means of a pressure air flow, an effective longer extent of path can be bridged without problems and without loss.